AIGLE, Switzerland (AP) -- Cycling's world governing body criticized world doping authorities and a French sports newspaper for alleging seven-time Tour de France champion Lance Armstrong used performance-enhancing substances six years ago.

The UCI said Friday it was still gathering information and had asked the World Anti-Doping Agency and the French laboratory which tested the samples taken from Armstrong in 1999 for more background. It also wanted to know who commissioned the research and who agreed to make it public.

"How could this be done without the riders' consent?" the UCI said.

Last month, Armstrong was accused of doping by L'Equipe, which reported that the blood booster EPO was found in six of his 1999 urine samples.

Armstrong has angrily denied the charges, saying he was the victim of a "witch hunt." He questioned the validity of testing samples frozen six years ago, and how the samples were handled.

"I'm pleased the UCI is investigating this entire matter thoroughly because any professional investigation will reveal that the allegations made by a French sports tabloid have no basis because I never used any performance-enhancing drugs," Armstrong said in a statement. "Based on the translation I read of the press release, I'm pleased that the UCI seems to be asking many of the right questions."

The UCI also asked WADA to say if it allowed the results to be disseminated, which the cycling federation says is a "breach of WADA's anti-doping code."

"We have substantial concerns about the impact of this matter on the integrity of the overall drug testing regime of the Olympic movement, and in particular the questions it raises over the trustworthiness of some of the sports and political authorities active in the anti-doping fight," the UCI said.

The UCI also said it had received no evidence of doping despite requests.

"The UCI has not to date received any official information or document" from anti-doping authorities or the laboratory reportedly involved in the testing of urine samples from the 1999 Tour de France, the cycling federation said.

UCI president Hein Verbruggen has asked for harsh sanctions against dopers and suggested Armstrong should face sanctions if he were shown to be guilty.

He also told Friday's Le Figaro that Armstrong had proposed before the Tour that all of his urine samples be kept for tests over the next 10 years.

UCI said it was still "awaiting plausible answers" to its requests to WADA and the laboratory.

"We deplore the fact that the long-established and entrenched confidentiality principle could be violated in such a flagrant way without any respect for fair play and the rider's privacy," it said.

UCI singled out WADA president Dick Pound for making "public statements about the likely guilt of an athlete on the basis of a newspaper article and without all the facts being known."

It also criticized the article in L'Equipe as "targeting a particular athlete."

L'Equipe said it would react of UCI's criticism in Saturday editions. Tour de France organizers had no immediate reaction, spokesman Matthieu Desplats said.

Claude Droussent, the editor of L'Equipe, denied his newspaper targeted Armstrong because he is American, and said it would have treated a French rider the same.

Armstrong retired after winning his seventh straight Tour title in July, but said this week he is considering a comeback. He plans to attend the Discovery Channel team training camp this winter.